Add Config Values for Enable SHA-256 Hashing Algorithm

[hisanhunais]

Purpose

With [1] and [2], the support for SHA-256 was given for certificate hashing algorithm in backend JWT generation. To enable this support, a config was provided. This PR provides the default value for the config and add this config to the deployment.toml by commenting its value

[1] wso2/carbon-apimgt#12365
[2] wso2/carbon-apimgt#12387

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 24.29%. Comparing base (93e2009) to head (131cad0).
Report is 7 commits behind head on master.

❗ Current head 131cad0 differs from pull request most recent head 0d67e24. Consider uploading reports for the commit 0d67e24 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #13444      +/-   ##
============================================
+ Coverage     20.27%   24.29%   +4.01%     
- Complexity     1034     1239     +205     
============================================
  Files           254      254              
  Lines         11495    11489       -6     
  Branches       1200     1200              
============================================
+ Hits           2331     2791     +460     
+ Misses         9135     8671     -464     
+ Partials         29       27       -2     

Flag	Coverage Δ
integration_tests	24.29% <ø> (+4.01%)	⬆️

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